1. Field of the Invention
This invention pertains generally to superconducting power transmission cables, and more particularly to conduction-cooling of high-temperature superconducting power transmission cables.
2. Description of Related Art
Current high-temperature superconducting (HTS) power transmission cable systems are cooled by convection using a coolant, such as liquid nitrogen, that circulates axially along the cable to keep the HTS cable below the superconducting transition temperature. This configuration requires a cable construction resembling a hose that must contain the coolant during operation. Coolant must be continually replenished in systems that do not recover the coolant. Cables are often hermetically sealed and coolant recovered, so as to reduce the cost of coolant production. Current cable designs are often limited to lengths of less than 200 meters due to these limitations. There are two basic HTS cable designs recognized for electric power transmission: the Warm Dielectric design (WD) and the Cold Dielectric Coaxial design (CDC). Examples can be found in Malozemoff AP, et al., “Power applications of high-temperature superconductors: status and perspectives,” IEEE Trans. Appl. Supercond. 2002, 12(1): 778-781, and Kelley, N. et al., “Application of HTS wire and cables to power transmission: state of the art and opportunities,” IIE Power Engineering Society Winter Power Meeting, January 2001, which describe current designs for superconducting power transmission cables.